<<<<<<However when I checked in online the day before my flight a different seat in row 17 appeared for that segment...

I was a Silver flying AMS-DTW December 30th and had diligently reserved window/exit seat 10j 90 days ahead of time. It was to be my first flight on an A330, and thanks to you great folks on FlyerTalk, I had that seat carefully staked out. But at the gate in AMS when they ran my boarding pass, the machine buzzed. The agent looked at it quizzically, and then told me that I had been reassigned to a new seat. Although at first I was concerned, I have to admit that 1G wasn't all that bad. ;